It has been demonstrated that chronic ethanol administration affects the ability of liver to regenerate in vivo by inhibiting 3H thymidine incorporation into DNA following partial hepatectomy (McNeil, G.E., Chen, T.S. and Leevy, C.M.: Hepatology 5: 43-48, 1985; Poso, H., Vaananen, H., and Poso, R.: Med Biol 58: 329- 336, 1980). More specifically ethanol has also been shown to inhibit hepatocyte DNA synthesis following hormonal stimulation by a number of agents including epidermal growth factor (EGF)(Carter, E.A. and Wands, J.R.: Biochem Biophys Res Commun 128: 767-774, 1985). In an attempt to understand the mechanism by which ethanol interferes with the normal processes of growth and development, we have undertaken an extensive study on the early metabolic changes induced by several hormones and growth factors in vivo. We have now identified the initial metabolite changes induced by platelet derived growth factor, epidermal growth factor and angiotensin in the rat in vivo. In addition, we have demonstrated a direct effect of ethanol on the normal metabolic action of EGF in vivo (Gerhart, M.J., Reed, B.Y. and Veech R.L.: submitted to Alcoholism: Clin Exp Res, 1987). Further studies are in progress to investigate the cause of the enzyme activity changes responsible for the observed metabolite changes in vivo.